SEPA
United States
Environmental Protection
Agency
Municipal Environmental Research
Laboratory
Cincinnati OH 45268
Research and Development
EPA-600/S2-81-069 June 1981
Project Summary
Soil Temperature and Sewage
Sludge Effects on Plant and
Soil Properties
C. C. Sheaffer, A M. Decker, R L. Chaney, G. C. Stanton, and D. C Wolf
A field study was conducted at the
University of Maryland Plant Research
Farm to evaluate the effects of soil
temperature on sewage sludge nutri-
ent release for corn growth. Survival
of bacterial indicator organisms as a
function of soil temperature was also
determined.
This Project Summary was devel-
oped by EPA's Municipal Environ-
mental Research Laboratory. Cincinnati,
OH, to announce key findings of the
research project that is fully docu-
mented in a separate report of the
same title (see Project Report ordering
information at back).
Experimental Design and
Procedures
The experimental design was a split-
plot with three replications. Target soil
temperature regimes (whole plots) of
ambient (mean value - 22 C), 16, 27,
and 35 C were maintained in 4.5 x 1.8-
m plots, of which 15x1.8-m sub-plots
received sludge rates of 0, 56, and 112
metric ton/ha. On a dry matter basis,
the sewage sludge contained 3.0% N,
2.0% P, 0.1 % K, 0.8% Ca, and 1.1 % Mg;
and 4000 /ug/g Zn, 2200/ug/g Cu, 140
/yg/g Pb, 170 //g/g Ni, and 16 /ug/g Cd.
Field corn (Zea mays L.) was planted
in the spring of 1975 and 1976 in each
plot, and radishes (Raphanus sativus L.)
were planted between the corn rows.
Corn was sampled at the following
stages: seedling (8 to 9 leaf), ear leaf
(anthesis), and stover and grain (hard
dent). Stover and grain yields were
measured. Ear leaf samples were analyzed
for P, K, Ca, and Mg, and all samples
were analyzed for Zn, Cu, Ni, Cd and Pb.
Forage quality of corn stover was also
determined. Radishes were harvested
prior to bolting.
Following removal of corn in the fall of
1975, oats (Avenasativa L, var. Norline),
wheat (Triticum aestivum L, var. Arthur),
rye (Secale cereale L, var. Balboa),
crimson clover (Trifolium incarnatum L,
var. Auburn), and arrowleaf clover (Tri-
folium vesiculosum Savi, var. Yuchi)
were planted. The temperature regula-
tion equipment was inactivated for the
tests with these crops. In the spring of
1976, forage of small grains was harvested
in the boot stage and legumes at 1/10
bloom; plant yields were not taken.
Sample preparation and assay for heavy
metals was as for corn tissue. The corn
and radish planting followed shortly
after harvest of these crops. All condi-
tions, including the sludge, were the
same as for the 1975 planting.
Soil cores were taken from each plot
at 0, 3, 7, 12, 20, 40, 56, and 68 weeks
following initiation of the study, and
available metals were determined by
double acid and diethylene triamine
pentaacetic acid (DTPA) extraction.
Filtrate was analyzed for Zn, Cu, Cd, and
Ni. Soil samples were also analyzed for
organic matter content, pH, and cation
exchange capacity At the conclusion of
the experiment, soil samples were
analyzed for water stable aggregation
and bulk density. Soil samples were also
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collected atO, 21, 49, 91, and 147 days
after sludge addition and analyzed for
fecal coliform.
Conclusions
Soil temperature had a pronounced
effect on corn growth. Below-ambient
soil temperature (16 C) significantly
reduced yields of grain and stover. This
was expected because corn is a warm
season plant that makes optimum growth
at temperatures of 24 to 30 C. The
largest increases in yields occurred as
soil temperature increased from 16 C to
ambient (22 C). Above ambient soil
temperatures produced no significant
grain or stover yield changes in 1975,
but in 1976, an increase in yields was
noted. The 1976 response may be
attributed to an increase in plant yield
potential by soil heating during an
abnormally cool spring. In both years,
plants were taller, had more leaves, and
matured earlier at 35 C than at 16 C.
Highest quality stover was produced at
16 C, possibly because of reduced lignin
biosynthesis and stem elongation.
Sewage sludge application had little
effect on grain or stover yields at most
soil temperatures in 1975, but grain
yields were significantly increased on
plots subjected to a 16 C soil tempera-
ture. In 1976, check plots had significantly
lower gram yields at all soil tempera-
tures than those to which sludge was
applied. Stover yields were significantly
lower for check plots than plots amended
with 112 ton/ha sludge at all tempera-
tures except 16 C where no significant
effect was observed.
Sewage sludge application increased
N, P, Mg, and Ca concentrations in corn
ear leaves in both years of the experi-
ment. Potassium levels were not in-
creased. Nutrients added in the sludge
increased concentrations in the ear
leaves and may be responsible for
higher yields from sludge amended
plots in 1976. Higher concentrations of
N, P, and K were found in corn ear
leaves from 35 C plots than from 16 C
plots in both years. Calcium concentra-
tions were consistently higher in ear
leaves from 16 C plots.
Sewage sludge application increased
the Zn, Cu, Cd, and Ni levels in corn
plants. Zn and Cu were present to the
largest extent in aerial portions of the
plant. Zn and Cd appeared to be trans-
located from soil to aerial tissues more
readily than did the other heavy metals
evaluated. Lead levels in plants were
not increased due to sewage sludge
application.
The effects of soil temperature on
heavy metal concentrations in plants
varied considerably according to year,
metals, and plant materials. Soil tem-
perature had no significant effect on Ni
and Pb concentrations in stover, grain,
ear leaves, or seedlings. Zinc levels in
ear leaves and seedlings from plants
grown on sludge amended plots were
significantly higher for both years at a
soil temperature of 35 C than at 16 C.
Soil temperature effects on stover Zn
concentrations were variable and pos-
sibly masked because of the effect of dry
matter. Lower Cu concentrations were
observed in ear leaves, stover, and
seedlings at 1 6 C ihan at other soil
temperatures. This was not significant
all years and for all sludge rates. Seedling
Cd concentrations were significantly
higher each year at 35 than at 16 C.
Cadmium levels in ear leaves and stover
were not significantly affected by soil
temperature.
Sewage sludge application resulted
in significant increases in soil organic
matter, pH, and DTPA and double acid
extractable metals. Organic matter
levels in sludge amended plots decreased
significantly during the 68 weeks of the
experiment. Available Zn and Cu con-
centrations as measured by DTPA ex-
traction increased from the start to the
end of the experiment. No consistent
changes occurred in Ni and Cd concen-
trations. Soil bulk density decreased
and soil aggregation increased as a
result of sewage sludge application.
Effects of soil temperature on soil
organic matter and DTPA extractable
metal levels were small and nonsignifi-
cant within soil samplings taken during
the experimental period. At all sludge
rates, 35 C and 27 C soil temperatures
resulted in a significant reduction in soil
pH by the conclusion of the experiment.
Ambient and 16 C soil pH values were
not significantly different. Soil tempera-
ture had no effect on bulk density or
aggregation.
Increases in sewage sludge applica-
tion rates significantly increased the
heavy metal concentrations in both
radishes and forages. Radish tops had
higher metal concentrations than roots.
The effects of temperature and sludge
treatment were more apparent on
radishes than on corn. Legumes grown
during winter months, when soil tem-
perature was not regulated, had higher
metal concentrations than did small
grams, but the legume or small grair
metal levels were not significantly
affected by residual soil temperature;
from the preceding series of tests.
Higher levels of heavy metals found ir
plants at 35 C versus 16 C soil tem
peratures appear to be a function o
temperature stimulation of plant uptake
and translocation processes, sinct
heavy metal availability to plants a:
measured by DTPA extraction was onl^
slightly affected by soil heating. Nc
residual temperature effect on meta
content of legumes or grasses was
observed.
Both temperature level and apphca
tion rate affected survival of indicate
bacteria. Fecal coliform and fecal strep
tococcus survived longer at the lowes
temperature (16 C), and the shortes
survival was found at the highest tem
perature (35 C). At the highest soi
temperature (35 C), the addition o
sludge at the high rate (112 metrii
ton/ha) resulted in the longer surviva
time for both of the indicator bacteria.
These data indicate that sludge addi
tion at high rates when soi I temperature;
are low would result in the greates
pathogen survival (about 2 logs reduc
tion in 50 days); low sludge additior
when soil temperatures are high woul(
result in the lowest rate of pathoger
survival (about 4 logs reduction in 5(
days).
The full report was submitted ir
partial fulfillment of Interagency Agree
ment EPA-IAG-D-X0376 with the U.S
Department of Agriculture, Beltsville
MD, under the sponsorship of the U.S
Environmental Protection Agency.
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C. C Sheaffer is with the University of Minnesota, St. Paul. MN 55108; A. M.
Decker is with the University of Maryland, College Park, MD 20742; Ft. L.
Chaney is with SEA-USDA, Beltsville, MD 20705; G. C. Stanton is with the
City of Baltimore, MD21203; andD. C. Wolf is with the University of Akransas,
Fayetteville, AR 72701.
G. K. Dotson is the EPA Project Officer (see below).
The complete report, entitled "Soil Temperature and Sewage Sludge Effects on
Plant and Soil Properties," (Order No. PB81-191 199; Cost: $11.00, subject to
change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Municipal Environmental Research Laboratory
U.S. Environmental Protection Agency
Cincinnati, OH 45268
* US GOVERNMENT PRINTING OFFICE 1981-757-01Z/7147
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Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
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